Ventilation/Perfusion

Question 0

What is the CO2 differential in the alveolus?

Answer 0

Alveolar: 40 mmHg CO2
Capillary: 46 mmHg CO2

Question 1

What is the normal oxygen differential in an alveolus?

Answer 1

Alveolar air: 100 mmHg O2

Capillary: 40 mmHg O2

Question 2

What is normal O2 differential in tissues?

Answer 2

Tissue: 5 mmHg O2
Capillary: 100 mmHg O2

Question 3

What is CO2 pressure differential in tissues?

Answer 3

Tissue: >40 mmHg CO2
Capillary: 40 mmHg CO2

Question 4

What is a respiratory quotient?

Answer 4

Produced CO2/consumed O2

Question 5

How do you calculate shunt blood flow?

Answer 5

Qs/Qt = ([O2]cap - [O2]art)/([O2]cap - [O2]vein)

Question 6

What benefit does oxygen delivery during pneumothorax give?

Answer 6

Creates pressure differential of N2 from PTX space, N2 gets reabsorbed and exhaled, decreasing space

Question 7

What are some situations with perfusion but no ventilation?

Answer 7

Obstructed airway, chronic bronchitis, acute pulmonary edema

Question 8

What are some situations with less perfusion but high ventilation?

Answer 8

PE, can be observed with COPD

Question 9

What does acidity change look like in terms of apex to bottom of lungs?

Answer 9

Increased acidity at bottom because higher CO2 (lower vent/perf ratio)